1. Technical Field
The present invention relates to a field emission device, a display adopting the same, and a method of manufacturing the same, and more particularly, to a field emission device which has improved focusing effect of electron beams, a display adopting the same, and a method of manufacturing the same.
2. Related Art
Display devices, which are the principal conventional information transmission media, have been typically used as monitors of PCs or TV receivers. Such display devices are largely classified into Cathode Ray Tubes (CRTs), which use high-speed emission of hot electrons, and flat panel display devices, which have been rapidly advancing. The flat panel display devices include liquid crystal display (LCD) devices, plasma display panels (PDPs), and field emission display devices (FEDs).
In the field emission display device, a strong electric field is formed between a field emitter and a gate electrode disposed on a cathode at a constant interval, so that electrons are emitted from the field emitter to impinge phosphors on an anode, thereby emitting light. The field emission display is a very thin display device, and is therefore attracting great attention in view of its thinness of several centimeters in overall thickness, a wide viewing angle, low power consumption, and a low fabrication cost.
The field emission display device utilizes substantially the same physical principle as the CRT. In other words, emissions emitted from the cathode are accelerated to collide with the anode, so that phosphors coated on the anode are excited to then emit light of a particular color. Unlike the CRT, however, the field emission display device uses a cold cathode material as an electron source.
The field emission display device includes a cathode formed on a substrate. Also, a gate electrode is formed on an insulating layer as an electron extracting electrode. A field emitter is provided within a hole through which part of the cathode is exposed.
In the field emission display device having the above-described structure, however, if trajectories of electron beams are not controlled, a desired color cannot be exactly displayed at a given pixel. Therefore, there is a need for an electron beam trajectory control technique which enables electrons emitted from a field emitter to be accurately transmitted to a desired pixel on an anode coated with a phosphor material.
With respect to an electron source having a focus gate electrode, a second insulating layer is additionally deposited over a gate electrode, and a focus gate electrode for controlling electron beam trajectories is formed thereon.
With respect to trajectories of electron beams emitted from emitters of the FED having the focus gate electrode, overfocused electrons deviate from a target phosphor layer region and excite a phosphor layer in another region, which results in deterioration of color purity. This undesirable result is caused by variation in the protruding directions of a carbon nanotube (CNT) used as an electron source.
To avoid the above-described concerns, U.S. Pat. No. 5,920,151 discloses a field emission display (FED) device having an imbedded focusing structure, which requires, however, an outgassing process for exhausting volatile gas from an organic material formed on a focus gate electrode, i.e., polyimide. This makes the disclosed FED difficult to be applied to a large-screen display field.